Specifically, the researchers looked at triclosan, a widely used antibacterial chemical, which you'll find in soap, deodorants, mouthwashes, toothpaste, bedding, and a whole bunch of other things. It's generally assumed to be safe for humans because it binds to proteins without becoming biologically available — plus there are limited ways that it gets into our bodies.

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Concerned by the fact that triclosan has been detected in waterways and human waste, some researchers set out to see how it effected muscle control, both in petri dishes and animal models. In vitro, they found the chemical impaired isolated heart muscle cells and skeletal muscle fibers from being able to contract properly by blocking calcium channel communication. Moving up to animal models, mice showed a 25% reduction in heart function after being exposed to the chemicals, an 18% reduction in grip strength for up to an hour after dosing; and fathead minnows that spent a week in contaminated water swam worse than those that hadn't.

Such effects are enough to put the animals at risk for predation. "We were surprised by the large degree to which muscle activity was impaired in very different organisms and in both cardiac and skeletal muscle," said co-author Bruce Hammock in a press release. "You can imagine in animals that depend so totally on muscle activity that even a 10-percent reduction in ability can make a real difference in their survival."

We're still a long way from showing there are directly negative effects on humans — after all, we'd require a much higher exposure than mice to feel the effects, but the ubiquity of the chemical has the authors worried.

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"In patients with underlying heart failure, triclosan could have significant effects because it is so widely used," co-author Nipavan Chiamvimonvat said. "However, without additional studies, it would be difficult for a physician to distinguish between natural disease progression and an environmental factor such as triclosan."

With more research, we may get a better idea about what's happening. In the meantime, you can just use normal soap and not worry about it.